Rae Votta spoke to Hogwarts employees…more specifically employees of the Wizarding World of Harry Potter at Universal Studios Hollywood – a theme park:

Before being hired park attendants are asked basic trivia questions such as the four Harry Potter houses.

If they pass the initial screening they get put into a week of intensive classroom training where they learn the ins and outs of Harry Potter trivia, since engaged fans are going to expect them to know it all.

All attendants have to play characters but for the most part they’re all non-Hogwarts students. They want park guests to feel special and unique about being the ones who get to go to Hogwarts.

Attendants also aren’t allowed to claim that they know any of the main characters personally. They are, after all, not part of the story.

And if someone asks about Voldemort? Attendants must look terrified and refer to him as “You Know Who”.

The theme park itself is set in between the third and fourth books – there are posters about Sirius black escaping and the upcoming Triwizard tournament.

It is also perpetually winter, which explains why visitors are unlikely to bump into even side characters like Cedric or Cho Chang, who are presumably at home for the holidays.